New PPV derivatives which contain electron-withdrawing CF3F 4phenyl group, poly[2-(2-ethylhexyloxy)-5-(2,3,5,6-tetrafluoro-4- trifluoromethylphenyl)-1,4-phenylenevinylene] (CF3F 4P-PPV), and poly[2-(4-(2-etylhexyloxy)-phenyl)-5-(2,3,5,6- tetrafluoro-4-trifluoromethylphenyl)-1,4-phenylenevinylene] (P-CF 3F4P-PPV), have been synthesized by GILCH polymerization. As the result of the introduction of the electron-withdrawing CF 3F4phenyl group to the phenyl backbone, the LUMO and HOMO energy levels of CF3F4P-PPV (3.14, 5.50 eV) and P-CF 3F4P-PPV (3.07, 5.60 eV) were reduced. The PL emission spectra in solid thin film are more red-shifted over 50 nm and increased fwhm (full width at half maximum) than solution conditions by raising aggregation among polymer backbone due to electron withdrawing effect of 2,3,5,6-tetrafluoro-4-trifluoromethylphenyl group. The EL emission maxima of CF3F4P-PPV and P-CF3F4P-PPV appear at around 530-543 nm. The current density-voltage-luminescence (J-V-L) characteristics of ITO/PEDOT/polymer/Al devices of CF3F 4P-PPV and P-CF3F4P-PPV show that turn-on voltages are around 12.5 and 7.0 V, and the maximum brightness are about 82 and 598 cd/m2, respectively. The maximum EL efficiency of P-CF 3F4P-PPV (0.51 cd/A) was higher than that of CF 3F4P-PPV (0.025 cd/A).
- Electron-withdrawing group
- Polymer light emitting diodes (PLEDs)
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